A grassed waterway is a to 48-metre-wide (157 ft) native

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

strip of

green belt A green belt is a policy and land-use zone designation used in land-use planning to retain areas of largely undeveloped, wild, or agricultural land surrounding or neighboring urban areas. Similar concepts are greenways or green wedges, which ...

. It is generally installed in the

thalweg In geography and fluvial geomorphology, a thalweg or talweg () is the line of lowest elevation within a valley or watercourse. Under international law, a thalweg is the middle of the primary navigable channel of a waterway that defines the boun ...

, the deepest continuous line along a

valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ove ...

watercourse A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams a ...

, of a cultivated dry valley in order to control

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

. A study carried out on a grassed waterway during 8 years in

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

showed that it can lead to several other types of positive impacts, e.g. on

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...

Distinctions

Confusion between "grassed waterway" and "vegetative filter strips" should be avoided. The latter are generally narrower (only a few metres wide) and rather installed along rivers as well as along or within cultivated fields. However,

buffer strip A buffer strip is an area of land maintained in permanent vegetation that helps to control air quality, soil quality, and water quality, along with other environmental problems, dealing primarily on land that is used in agriculture. Buffer strip ...

can be a synonym, with shrubs and trees added to the plant component, as does a

riparian zone A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

Runoff and erosion mitigation

Runoff Runoff, run-off or RUNOFF may refer to: * RUNOFF, the first computer text-formatting program * Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed * Runoff or run-off, a stock marke ...

generated on cropland during storms or long winter rains concentrates in the

where it can lead to rill or gully erosion. Rills and gullies further concentrate runoff and speed up its transfer, which can worsen damage occurring downstream. This can result in a

muddy flood A muddy flood is produced by an accumulation of run-off over agricultural land. Sediments are picked up by the run-off and carried as suspended matter or bed-load. Muddy floods are typically a hill-slope process, and should not be confused with mu ...

. In this context, a grassed waterway allows increasing soil cohesion and roughness. It also prevents the formation of rills and gullies. Furthermore, it can slow down runoff and allow its re-infiltration during long winter rains. In contrast, its infiltration capacity is generally not sufficient to reinfiltrate runoff produced by heavy spring and summer storms. It can therefore be useful to combine it with extra measures, like the installation of earthen dams across the grassed waterway, in order to buffer runoff temporarily.Evrard, O., Vandaele, K., van Wesemael, B., Bielders, C.L, 2008. A grassed waterway and earthen dams to control muddy floods from a cultivated catchment of the Belgian loess belt. Geomorphology 100, 419-428.

References

External links

*
Water Agency of the Melsterbeek river, in Belgium (agency that had a pioneer role to implement erosion control measures in central Belgium)
{{DEFAULTSORT:Grassed Waterway Sustainable design Environmental engineering Environmental soil science Hydraulic engineering Ecological restoration Habitats Habitat Landscape Permaculture Sustainable agriculture Water pollution Water and the environment